Astronomers have detected a bridge of matter extending from a galaxy, apparently, towards nothing.
Neil Trentham, Ole Moller and Enrico Ramirez-Ruiz, at the Institute of Astronomy, Cambridge, believe their finding means an invisible galaxy, made entirely of dark matter, is lurking beside UGC 10214.
Astronomers believe that up to 90% of the Universe is made of non-luminous material that betrays its presence only through the action of its gravitational field. What this dark matter is remains a mystery.
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The group鈥檚 work, suggests that dark matter galaxies might eventually be found to outnumber ordinary galaxies by a hundred to one.
Galactic collision
When galaxies collide it is common to see bridges of luminous material being dragged from one to the other. Only in active galaxies are jets of material seen emanating from individuals.
But despite UGC 10214鈥檚 apparent isolation, Trentham believes visible trail is a bridge: 鈥淚t鈥檚 too thick to be a jet from an active galaxy. Also, some of the material is made up of stars and a jet would not push out stars.鈥�
Trentham has been working on formation theories for dark galaxies and believes that they are celestial latecomers, incapable of making stars.
He told 快猫短视频: 鈥淕alaxies grow from perturbations in dark matter. Normal galaxies began forming in the couple of billion years after the Big Bang. As the haloes grow, they pull in gas to form stars.
鈥淣ow imagine five to 10 billion years after the Big Bang. The gas sitting out between the galaxies has been heated by starlight and is travelling fast. A late forming halo can no longer hold onto it because its speed is so high. And without gas, the galaxy cannot form stars.鈥�
Possible candidates for dark matter include subatomic particles or failed stars, called brown dwarfs. If it is the latter, Trentham believes it may be possible to see these dark galaxies by their infrared glow.
The research will be published in Monthly Notices of the Royal Astronomical Society.